/*
 *
 * Copyright (c) 2006/2007 Sam Collett (http://www.texotela.co.uk)
 * Licensed under the MIT License:
 * http://www.opensource.org/licenses/mit-license.php
 * 
 * Version 1.0
 * Demo: http://www.texotela.co.uk/code/jquery/numeric/
 *
 * $LastChangedDate: 2007-05-29 11:31:36 +0100 (Tue, 29 May 2007) $
 * $Rev: 2005 $
 */
 
/*
 * Allows only valid characters to be entered into input boxes.
 * Note: does not validate that the final text is a valid number
 * (that could be done by another script, or server-side)
 *
 * @name     numeric
 * @param    decimal      Decimal separator (e.g. '.' or ',' - default is '.')
 * @param    callback     A function that runs if the number is not valid (fires onblur)
 * @author   Sam Collett (http://www.texotela.co.uk)
 * @example  $(".numeric").numeric();
 * @example  $(".numeric").numeric(",");
 * @example  $(".numeric").numeric(null, callback);
 *
 */
jQuery.fn.numeric = function(decimal, callback)
{
	decimal = decimal || ".";
	callback = typeof callback == "function" ? callback : function(){};
	this.keypress(
		function(e)
		{
			var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;
			// allow enter/return key (only when in an input box)
			if(key == 13 && this.nodeName.toLowerCase() == "input")
			{
				return true;
			}
			else if(key == 13)
			{
				return false;
			}
			var allow = false;
			// allow Ctrl+A
			if((e.ctrlKey && key == 97 /* firefox */) || (e.ctrlKey && key == 65) /* opera */) return true;
			// allow Ctrl+X (cut)
			if((e.ctrlKey && key == 120 /* firefox */) || (e.ctrlKey && key == 88) /* opera */) return true;
			// allow Ctrl+C (copy)
			if((e.ctrlKey && key == 99 /* firefox */) || (e.ctrlKey && key == 67) /* opera */) return true;
			// allow Ctrl+Z (undo)
			if((e.ctrlKey && key == 122 /* firefox */) || (e.ctrlKey && key == 90) /* opera */) return true;
			// allow or deny Ctrl+V (paste), Shift+Ins
			if((e.ctrlKey && key == 118 /* firefox */) || (e.ctrlKey && key == 86) /* opera */
			|| (e.shiftKey && key == 45)) return true;
			// if a number was not pressed
			if(key < 48 || key > 57)
			{
				/* '-' only allowed at start */
				if(key == 45 && this.value.length == 0) return true;
				/* only one decimal separator allowed */
				if(key == decimal.charCodeAt(0) && this.value.indexOf(decimal) != -1)
				{
					allow = false;
				}
				// check for other keys that have special purposes
				if(
					key != 8 /* backspace */ &&
					key != 9 /* tab */ &&
					key != 13 /* enter */ &&
					key != 35 /* end */ &&
					key != 36 /* home */ &&
					key != 37 /* left */ &&
					key != 39 /* right */ &&
					key != 46 /* del */
				)
				{
					allow = false;
				}
				else
				{
					// for detecting special keys (listed above)
					// IE does not support 'charCode' and ignores them in keypress anyway
					if(typeof e.charCode != "undefined")
					{
						// special keys have 'keyCode' and 'which' the same (e.g. backspace)
						if(e.keyCode == e.which && e.which != 0)
						{
							allow = true;
						}
						// or keyCode != 0 and 'charCode'/'which' = 0
						else if(e.keyCode != 0 && e.charCode == 0 && e.which == 0)
						{
							allow = true;
						}
					}
				}
				// if key pressed is the decimal and it is not already in the field
				if(key == decimal.charCodeAt(0) && this.value.indexOf(decimal) == -1)
				{
					allow = true;
				}
			}
			else
			{
				allow = true;
			}
			return allow;
		}
	)
	.change(
		function()
		{
			var val = this.value;
			if(val.length > 0)
			{
				// get caret (cursor) position
				var caret = $.fn.getSelectionStart(this);

				// prepend a 0 if necessary
				if(decimal != "")
				{
					// find decimal point
					var dot = val.indexOf(decimal);
					// if dot at start, add 0 before
					if(dot == 0)
					{
						this.value = "0" + val;
					}
					// if dot at position 1, check if there is a - symbol before it
					if(dot == 1 && val.charAt(0) == "-")
					{
						this.value = "-0" + val.substring(1);
					}
					val = this.value;
				}

				// if pasted in, only allow the following characters
				var validChars = [0,1,2,3,4,5,6,7,8,9,'-',decimal];
				// get length of the value (to loop through)
				var length = val.length;
				// loop backwards (to prevent going out of bounds)
				for(var i = length - 1; i >= 0; i--)
				{
					var ch = val.charAt(i);
					// remove '-' if it is in the wrong place
					if(i != 0 && ch == "-")
					{
						val = val.substring(0, i) + val.substring(i + 1);
					}
					var validChar = false;
					// loop through validChars
					for(var j = 0; j < validChars.length; j++)
					{
						// if it is valid, break out the loop
						if(ch == validChars[j])
						{
							validChar = true;
							break;
						}
					}
					// if not a valid character, or a space, remove
					if(!validChar || ch == " ")
					{
						val = val.substring(0, i) + val.substring(i + 1);
					}
				}
				// remove extra decimal characters
				var firstDecimal = val.indexOf(decimal);
				if(firstDecimal > 0)
				{
					for(var i = length - 1; i > firstDecimal; i--)
					{
						var ch = val.charAt(i);
						// remove decimal character
						if(ch == decimal)
						{
							val = val.substring(0, i) + val.substring(i + 1);
						}
					}
				}
				// set the value and prevent the cursor moving to the end
				this.value = val;
				$.fn.setSelection(this, caret);
			}
		}
	)
	.blur(
		function()
		{
			var val = jQuery(this).val();
			if(val != "")
			{
				var re = new RegExp("^\\d+$|\\d*" + decimal + "\\d+");
				if(!re.exec(val))
				{
					callback.apply(this);
				}
			}
		}
	);

	// Based on code from http://javascript.nwbox.com/cursor_position/ (Diego Perini <dperini@nwbox.com>)
	$.fn.getSelectionStart = function(o)
	{
		if (o.createTextRange)
		{
			var r = document.selection.createRange().duplicate();
			r.moveEnd('character', o.value.length);
			if (r.text == '') return o.value.length;
			return o.value.lastIndexOf(r.text);
		} else return o.selectionStart;
	}

	// set the selection, o is the object (input), p is the position ([start, end] or just start)
	$.fn.setSelection = function(o, p)
	{
		// if p is number, start and end are the same
		if(typeof p == "number") p = [p, p];
		// only set if p is an array of length 2
		if(p && p.constructor == Array && p.length == 2)
		{
			if (o.createTextRange)
			{
				var r = o.createTextRange();
				r.collapse(true);
				r.moveStart('character', p[0]);
				r.moveEnd('character', p[1]);
				r.select();
			}
			else if(o.setSelectionRange)
			{
				o.focus();
				o.setSelectionRange(p[0], p[1]);
			}
		}
	}

	return this;
}